Increased fructose-lysine of nail protein and blood glucose control in diabetic patients.

Furosine, which was formed by acid hydrolysis of fructose-lysine, was determined and used as an indicator of glycosylated protein. The diabetic patients had significantly higher fructose-lysine levels in finger nails than healthy subjects [10.8 +/- 4.6% (mean +/- S.D.) vs 4.2 +/- 1.1%]. The best correlation was found between the fructose-lysine value and the fasting blood glucose level determined 3 to 5 months before sampling nails in diabetics. These results suggest that the furosine derived from fructose-lysine in finger nails may become an indicator of blood glucose control during the past 3 to 5 months in diabetics.